1. Technical Field
The present invention generally relates to an electroplating method, and particularly, relates to an electroplating method for an insulative substrate.
2. Discussion of Related Art
Properties of carbon fibers such as high tensile strength, low weight, low thermal expansion, high electrical conductivity and heat conductivity make it very popular in many fields such as aerospace and motorsports. Generally, carbon fibers are widely employed in composite materials to improve performance thereof. For example, a copper-carbon fiber composite is disclosed in Keiidhi Kuniya et al. Development of Copper-Carbon Fiber Composite for Electrodes of Power Semiconductor Devices, IEEE Transactions on Components, Hybrids, and Manufacturing Technology, vol. 6, No. 4, pp. 467-472, Dec. 1983.
It is to be understood that in metal-carbon fiber composite, carbon fibers and metal cannot thoroughly soaked with each other due to the differences of surface properties. In order to improve a bonding between metal and carbon fibers, carbon fibers are usually pre-processed using electroless plating, electroplating, physical vapor deposition, or chemical vapor deposition. Electroplating is highly preferred for its simple process, low cost and high level plating layer.
Currently, carbon fibers are immersed in a plating bath and connected to an electrode during a plating process, a redox reaction occurs on surfaces of carbon fibers and plating layer is thereby deposited. However, a current distribution density is non-uniform on surfaces of carbon fibers; as a result, deposition speed of metal particles is also non-uniform. Specifically, the closer the carbon fibers are to the electrode, the higher the particles deposition speed. Therefore, the obtained plating layer is non-uniform, metal-carbon fiber composite made from such carbon fibers can't reach its expected performance. Therefore, there is a desire to develop a method of forming a uniform plating layer.